1. Field of the Invention
The present invention relates to the field of distributors for pasty products having a piston sliding tightly within a tubular body and passing up to a distribution head, as well as pumping means controlled by an actuator and expulsion valve or for closing a distribution passage or outlet for the pasty product. The term "pasty product" herein designates any product which can be distributed by such a distributor, no matter whether it is called a paste, a gel or a cream.
2. Description of Related Art
FR-A-2 577 076 describes a distributor in accordance with the above definition and with two embodiments. In the first embodiment of the bottom piston is provided with a return-preventing metal skirt and moves upwards under the effect of the vacuum caused by the discharge of the product from the chamber surmounting the piston, the underside of the piston being at atmospheric pressure. In the second embodiment the bottom piston is drawn upwards in stepwise manner towards the outlet port during successive uses of the distributor by a connecting rod coupled to the actuating lever, in such a way that the piston rises along the rod whenever the latter is driven in.
European patent application EP-A-213 048 248 (=FR-A No. 2 585 439) of the present Applicant describes a distributor with a sliding piston rising by vacuum action, as in the first aforementioned embodiment and which has a distribution head comprising:
pumping means constituted by a deformable tubular member having above its base fixed to the top of the tubular body a deformable cover or web and an upper tube;
an actuator having an outer tubular part fixed to the top of the tubular body and an inclinable central part connected to said fixed outer part, said inclinable central part carrying beneath a bearing web a distribution duct having a lateral outlet portion, as well as the bottom of a longitudinal shaft into which issues said outlet portion, said shaft tightly nesting the upper tube of the deformable tubular pumping member;
the upper tube of the pumping member terminates by a flexible upper lip, which is applied beneath the bearing web of the actuator, said flexible lip and said bottom surface of the bearing web respectively forming the flap and the seat of a valve for expelling the pasty product in the distribution duct towards the outlet port;
the distributor also comprising a valve for the suction of the pasty product from the tubular body into the deformable tubular member (or forcing back the product into said tubular member) through orifices at the top of the tubular body, said valve being constituted by a lower flexible tubular lip of said tubular member and by a central bearing surface of the top surface of said top.
With distributors of the aforementioned type and with a modified suction valve, it has been found that the force for distributing the pasty product and which has to be exerted on the actuator bearing web was very high, namely 2.5 kg in place of the desirable 1.5 kg and in this case with a return time to the initial position or cycle time of 2 to 3 seconds, which is acceptable. In general terms with the tested distributors, it has been found that the expulsion forces were excessive, as were the return times.